We can make them better

Upgrades to the 1.5, 1.6 and 1.9 engines that make them go farther or faster
Post Reply
Fatmobile
Global Moderator
Posts: 7564
Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

We can make them better

Post by Fatmobile »

Time to start building a database on ways to make the IDI diesels go faster down the road.
farther down the road on a measure of fuel.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
ibizz
Cetane Booster
Posts: 34
Joined: Wed Dec 29, 2010 8:06 am

Post by ibizz »

advancing the pump
open the fuel screw in pump
work in admission to flow more and beter air .
like dynamic admission
larger exaust
direct exaust or only with final silencer .
sport air filter
port and polish
vwtyp133
Turbo Charger
Posts: 532
Joined: Thu Dec 05, 2002 9:03 pm
Location: SoCal

Re: We can make them better

Post by vwtyp133 »

Strange... with all my lurking around here, this is the first I'd seen this thread! Expected a bunch more previously unknown secrets. :roll:

A strong "Yes" vote for the previously-mentioned upgrades for performance & power. The colder intake air (weather permitting) is obvious, but I'd always been told that a larger exhaust wouldn't help. Wrong... it helps a lot, especially if you've messed with the better air intake and adjusted for more top fuel delivery. I dumped the resonator & went 2.25" all the way back to a short glasspack & side exit for a noticeable improvement in power (yeah, it's louder but not that bad). Driven carefully it seems that it might improve the fuel mileage also, relative to the factory's constipated pea shooter-sized exhaust system.

The very sharp VW tech from whom I bought my first non-Rabbit diesel, a '79 Dasher sedan (1.5NA), had modded the injectors with some M-B shims to raise their break pressure to about 2500psi. That definitely helped to boost both power & mileage a bit. P/O said he used to hold it at a steady (indicated) 100mph for several hours at a time on long road trips!

Side note: best (corrected for speedo/odo error) mileage it got for me was on a mixed 400-mile trip of highway/in town/mountain (driving @ average 60mph on highway), loaded to the max with 4 adults & gear, plus a huge crammed-full Thule 'Pod' on top: 68.7mpg. Surprisingly that's within 3-4mpg of the top highway mileage we got out of the smaller/lighter '77 Rabbit 1.5NA (bone stock), so on a 'theoretical' highway-only road trip, that Dasher sedan could have easily beaten the Rabbit's best mpg. Why? The injectors' higher break pressure? Aerodynamics?

After that sedan was totalled by a drug-crazed red light runner's Chevy pickup :evil: , the best that same exact engine/trans combo ever got in the '80 Dasher station wagon was 54mpg. Since the 2 Dashers share identical front profiles, IMO cleaner rear end aerodynamics must matter a lot more that usually considered by non-engineering types like myself. When time & budget permit, the wagon will get some home-brewed attempts at aero-improvements, as well as a wide-ratio 5-speed & intercooled 1.6TD power. Hopefully I'll have more IDI improvements to report then.

Hope this wasn't too O/T.
J.R.
SoCal
Post Reply